"He probably doesn't even know I exist at the moment," Mathison told Channel 10's The Project.

"It is such a safe seat he's probably thinking there is not a challenge on. But when I saw him launch his campaign at the surf club and talk about what he was going to do with the electorate ... I thought for 15 years he's been promising the same things."

The former Australian Idol host is making his election tilt in a seat that includes the monied suburbs of Manly, Mosman and Neutral Bay.

The father-of-two supports marriage equality, refugees and climate change and has previously said he will be focusing on the youth vote in the electorate.

He has also said he wants to run against Abbott in a bid "to hold him to account".